The ultrastructure of fibrocystic disease of the breast

Twenty-two cases of fibrocystic disease were studied with light and electron microscopes. Histologically, the manifestations of fibrocystic disease are divided into five groups presenting a consistent light- and electron-microscopic appearance that includes: blunt duct adenosis, epithelial cell hyperplasia, sclerosing adenosis, “myoepithelial cell proliferation,” cyst with atrophic epithelium and cyst with apocrine changes. Fibrous stroma, lymphocytic infiltration and other features found with fibrocystic disease are not described here because of their presence in conditions other than fibrocystic disease. On the basis of the present study it is concluded that fibrocystic disease involves both epithelial and myoepithelial cells of the mammary duct.